Cytomegalovirus (CMV) retinitis and other ocular opportunistic infections (OIs) are a major cause of visual loss and morbidity among patients with AIDS. Although the epidemiology of CMV retinitis has been altered by highly active antiretroviral therapy (HAART), CMV retinitis remains among the most common OIs in patients with AIDS. Furthermore, there appear to be subtle abnormalities of vision (detected on contrast sensitivity and visual field testing) among patients with AIDS without ocular OIs, the long-term consequences of which are unknown. The Longitudinal Study of Ocular Complications of AIDS (LSOCA) is a multicenter, prospective, observational study of patients with AIDS. As of 1 June 2002, 1,337 patients with a diagnosis of AIDS have been enrolled, of whom 348 (26%) had a major ocular complication (94% of which were CMV retinitis). Projected enrollment by August 2003 is 1,700 patients. The objectives of the study are: 1) to determine the characteristics (clinical, virologic, and immunologic) of and risk factors for CMV retinitis and other ocular complications of AIDS in the era of HAART; 2) to monitor trends in the incidence and prevalence of CMV retinitis and other ocular complications of AIDS; and 3) to evaluate the outcomes of CMV retinitis and other ocular complications of AIDS and determine risk factors for adverse outcomes. Over the next five years an additional 500 patients will be enrolled in the study, to replace those lost to mortality and withdrawal, thereby maintaining a stable population of patients under followup. Participants will continue in followup for the duration of the study. All patients will be on a 3-month followup schedule. For patients with a major ocular complication, all followup visits will be clinic visits. For patients without a major complication, followup visits will alternate between clinic followup visits and telephone followup. Data will be collected from medical history, visual function testing, eye examinations, fundus photographs, quality of life assessment, laboratory studies, and collection of plasma and blood cells for banking. Banked specimens also will be analyzed for CMV DNA and HIV RNA levels. Outcomes of interest include the incidence of CMV retinitis, incidences of other ocular complications, visual outcomes, and mortality. Other outcomes of interest include sequelae of AIDS-related eye disease (e.g., retinal detachment), quality of life, and the effect of therapies on ocular disease. With an estimated 11,250 person-years of follow-up by 2008, LSOCA will be adequately powered to detect clinically meaningful relative risks even for uncommon events.